1. Field of the Invention
The present invention relates to water purification systems, and more particularly to domestic water purification systems employing modular filter assemblies utilizing granulated filtration media.
2. Discussion of the Related Art
Purification of drinking water prior to domestic use is becoming increasingly important to many consumers. Water is usually purified to one extent or another by most municipalities prior to being supplied to consumers. Such municipal purification systems are, however, often inadequate and, in any event, are incapable of removing many contaminants which adversely affect the taste of drinking water and which are introduced into drinking water between the municipal purification site and the residences being serviced by the municipality. For example, chlorine, chlorine by-products, rust, or even lead are often present in city and/or residential water pipes and may be picked up by water as it flows through the pipes. In addition, rural residences often have no means of purifying drinking water prior to use.
These factors have given rise to an ever increasing demand for on-site water purification systems. Filtration systems employing granulated media including activated charcoal and/or other filtration media have gained increased acceptance in many domestic applications because they remove many contaminants not removable by fibrous filters. Domestic drinking water purification systems have, however, heretofore suffered from several drawbacks and disadvantages limiting their acceptability to many consumers.
For instance, many water purification systems are unacceptably bulky and are unsuitable for residences having limited countertop or cabinet space. This problem can be alleviated somewhat by employing a relatively thin filter which can be installed in unused spaces such as the one which is ordinarily located behind the kitchen faucet. One such filter assembly is disclosed in U.S. Pat. No. 5,116,502, which issued to Ferguson on May 26, 1992. Ferguson discloses a filter having a housing which is sufficiently narrow to be installed behind a kitchen faucet and which is connectable to the kitchen faucet.
The filter assembly disclosed by Ferguson suffers several drawbacks. The filter assembly has inlets and outlets which are located relatively remote from one another on top of the filter housing, and is thus relatively bulky. The filter housing, though narrower than some other such housings, is still relatively wide and is unsuitable for mounting in many locations, such as inside an appliance such as a refrigerator or a freezer. Ferguson's filter assembly also is difficult to fabricate and employs a solid filter medium which is not as well suited for removing contaminants from drinking water as are many granulated filter media.
A filter employing a granulated filter medium is proposed by U.S. Pat. No. 4,693,823, which issued to Matchett on Sep. 15, 1987. The granulated filter medium is contained in an annular filter housing having inwardly-facing ridges formed in the side walls thereof. The ridges are said to create a turbulence along the surfaces of the inner walls of the housing so as to prevent the formation of channels which, according to the patent disclosure, would otherwise occur if water were to be permitted to flow laminarly through the housing.
The ridged housing of the filter assembly disclosed by Matchett exhibits several drawbacks. The ridges are formed from relatively sharp angles and would thus appear to weaken the sides of the housings. The thus weakened side walls of the housing could bow outwardly under fluid pressure within the housing, thereby promoting the very channeling which the filter is designed to prevent. The ridges on opposed sides of the housing are also aligned with one another and thus do not produce serpentine fluid flow through the housing, thus further increasing the pressures within the filter and increasing the dangers of channeling. The filter assembly disclosed by Matchett is also relatively bulky and lacks any devices facilitating its coupling to a dispenser or to a source of untreated water. This filter assembly is also insufficiently strong to withstand the pressure of water flowing through the filter, and thus must be enclosed in a separate housing.